A membrane valve, which is commonly used in the area of refrigeration, and particularly used in hermetic and/or semi-hermetic compressors to promote the refrigeration effect, is well known in the art. The membrane valve, allows gas to be transferred from one chamber to the other, according to a pre-determined frequency.
In regards to the dynamics of operation, membrane valves are comprised of an external section to be attached to the housing of the body of a compressor or the like and at least one internal section (membrane or reed) that is free to move (oscillate) in relation to the first section. The internal section is designed to be positioned over an area which is the intermediate point between a fluid entry duct and a suction chamber and which transfers such fluid to a chamber equally furnished with an exhaust valve. In this manner, at least one of the above mentioned internal sections oscillates in accordance to the behavior of the chamber and, in this condition, the exhaust valve is closed. In a following stage, where the fluid is compressed into the chamber, the membrane valve closes, while the exhaust valve is opened, thus transferring the fluid to another duct, with the piston of a hermetic compressor providing the suction and transfer functions.
There exists an extensive variety of single-piece membrane valves, generally made of high carbon or stainless steel. Such membrane valves are described in detail in U.S. Pat. No. 6,227,825 and Brazilian Patent No. P19702470-8, both of which are incorporated herein by reference. The limits associated with such monolithic structures are also described in detail in U.S. Pat. No. 6,227,825.
A multi-piece membrane valve is described in detail in U.S. Pat. No. 6,227,825 which overcomes many of the disadvantages associated with monolithic structure of these single-piece membrane valves. The external section and internal section of the membrane valve is joined together by laser welding using a laser, brazing, gluing or the equivalent. Although the connection arrangement disclosed in U.S. Pat. No. 6,227,825 solves many of the problems of past membrane valves as described in Brazilian Patent No. P19702470-8, the connection arrangement has some disadvantages. The consistency and quality of the connection arrangement formed by laser welding can vary from part to part. Also, the costs associated with laser welding can be higher that with using a single piece stamping process. Furthermore, because a weld bead generally extends some distance above the surface of the body or reed of the piece, the weld does not allow or makes it difficult to form a piece wherein the full top surface and/or the full bottom surface of the membrane valve lies in the same plane.
The present invention is directed to a further improvement to the multi-piece membrane valve as described in detail in U.S. Pat. No. 6,227,825.